A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
Zepu County, the abbreviation of "Zepuleshan", gets its name from Zele Kushan River. Zeplesan, Tajik, means "river of gold". The river has sand gold, hence its name. Zep, also known as Boskamu, is the pronunciation of "Persian Tikan" in Uyghur language, meaning "fertile land". Belongs to the Kashgar region of Xinjiang, located in the southwest of Xinjiang, the northern foot of Kunlun Mountains, the eastern side of Karakoram Mountains, the western edge of the Taklimakan Desert. It is bounded by the Yeerqiang River in the west, Shache County in the west, Yecheng County in the east and southeast, and Yecheng County in the southwest. It covers an area of 999.96 square kilometers with a population of 200000. Zepu County is 1215-1490 meters above sea level and belongs to warm temperate continental arid climate. The annual average temperature is 11.4 ℃, the extreme maximum temperature is 39.5 ℃, and the extreme minimum temperature is-2.